Immunosuppression effected by macrophage surfaces.

Heat-killed macrophages (but not six other types of cells tested) suppress Mishell-Dutton cultures by a mechanism that does not adversely affect cell viability. The suppressive effect is abolished by treatments that inactivate receptors for cytophilic antibody. We suggest macrophages may absorb, and thus render inoperative, factors which are necessary for lymphocyte cooperation.